Hi Gilbert, there's two options:
1) Turn on the activity tracking in GP. Administration > Setup > Activity Tracking. Change the activity type drop-down to File Tracking. Then check "Deletions to Trx files." Then you'll have to go through the list of users underneath and check the Activate checkbox for each company listed you want to track.
The report is very basic -- date, username, transaction number showing it was deleted.
If you add users in the future, this is not automatically turned on by default, so you'll have to remember to turn on this tracking on for users.
One caveat about this for sales orders: when sales transactions are moved from the work to history tables, this is also considered a delete and will be logged on the report.
Not ideal.
2) Look into a third-party auditing solution like Rockton Software's Auditor or FastPath's Audit Trail. These give you options that allow you much more detailed control on the auditing setup. These also work somewhat independently of GP, so if other systems that are interacting with the GP data do something to transactions, these tools can report on that too.
I hope this helps.
Joe
